[hibernate-issues] [Hibernate-JIRA] Commented: (HHH-5465) HQL left join fetch of an element collection following a left join fetch of a one-to-one relationship causes NullPointerException

[Andrew Tolopko (JIRA)]

    [ http://opensource.atlassian.com/projects/hibernate/browse/HHH-5465?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=38045#action_38045 ] 

Andrew Tolopko commented on HHH-5465:
-------------------------------------

Commenting out lines 373-374 in org.hibernate.hql.ast.tree.FromElementFactory in createCollectionJoin() appears to fix the reported issue, although I cannot say what ill effects this may have elsewhere, since I have not attempted to run the full set of Hibernate tests with this patch in place.

373: //origin.setText( "" ); // The destination node will have all the FROM text.
374: //origin.setCollectionJoin( true ); // The parent node is a collection join too (voodoo - see JoinProcessor)

Interestingly, note that line 372 was commented out back in 2005 to address HHH-242.

Finally, please note that in the originally attached test code, the classes EntityB and EntityC erroneously include an EntityB data member, which should be removed. The existence or absence of these data members does not affect the validity of the test code; it problem persists in both cases.  I will attach a new file containing the corrected classes for EntityB and EntityC, as well as the patched FromElementFactory class, to demonstrate the fix.


> HQL left join fetch of an element collection following a left join fetch of a one-to-one relationship causes NullPointerException
> ---------------------------------------------------------------------------------------------------------------------------------
>
>                 Key: HHH-5465
>                 URL: http://opensource.atlassian.com/projects/hibernate/browse/HHH-5465
>             Project: Hibernate Core
>          Issue Type: Bug
>          Components: query-hql
>    Affects Versions: 3.5.4
>         Environment: Hibernate 3.5.4, Postgresql 8.4, Java 6
>            Reporter: Andrew Tolopko
>         Attachments: hibernate-left-fetch-join-element-collection.zip, log.txt
>
>
> HQL queries of the form 
> "from EntityA a left join fetch a.entityB b left join fetch b.items"
> fail with a NullPointerExeption when EntityA and EntityB have a one-to-one (@OneToOne) relationship and EntityB.items is an element collection (@ElementCollection, aka collection of values).  
> For comparison, the following HQL queries are all admissible (which intends to demonstrate that no particular clause of the the above HQL is incorrect):
> "from EntityB b left join fetch b.items"
> "from EntityA a left join fetch a.entityB"
> "from EntityA a left join fetch a.entityB.items"
> "from EntityA a left join fetch a.entityCs c left join fetch c.items" (where EntityA and EntityC have a one-to-many (@OneToMany) relationship, and EntityC.items is an element collection)
> Test code is attached.  The log output along with thrown exception is attached as log.txt.

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